Suppose you ask someone to use something that belongs to you, so that you can benefit from their use of it. For example, you (voluntarily) give a camera to someone you know to take a picture (of you). He drops it, causing damage.

Should he pay for all/ half/ none of the damages he (accidentally) caused? Do you have any standing to demand payment?

The damage would not have happened if device owner did not ask the other person to use it to benefit the owner.

What does the Jewish law say? Philosophically, what is the right thing to do from the standpoint of the person who owns the camera and from the standpoint of the person who caused the damage?

I don't think that's what that rule means. בעליו עמו means if I guard, rent or borrow an object from someone who is currently employed by me then I am exempt from damages to that object not directly caused by me even if the original owner later stops being employed by me. Physical proximity is irrelevant.
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Double AA♦Apr 9 '13 at 16:26

@DoubleAA - I added a more relevant answer. I left the old one so that your comment is in context.
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Danny SchoemannApr 11 '13 at 8:24